On Sun, Sep 18, 2022 at 11:52:43AM -0400, guoren@xxxxxxxxxx wrote: > +ENTRY(call_on_stack) > + /* Create a frame record to save our ra and fp */ > + addi sp, sp, -RISCV_SZPTR > + REG_S ra, (sp) > + addi sp, sp, -RISCV_SZPTR > + REG_S fp, (sp) > + > + /* Save sp in fp */ > + move fp, sp > + > + /* Move to the new stack and call the function there */ > + li a3, IRQ_STACK_SIZE > + add sp, a1, a3 > + jalr a2 > + > + /* > + * Restore sp from prev fp, and fp, ra from the frame > + */ > + move sp, fp > + REG_L fp, (sp) > + addi sp, sp, RISCV_SZPTR > + REG_L ra, (sp) > + addi sp, sp, RISCV_SZPTR > + ret > +ENDPROC(call_on_stack) IIRC x86_64 moved away from a stack-switch function like this because it presents a convenient exploit gadget. I'm not much of an exploit writer and I've no idea how effective our inline stategy is, perhaps other can comment.
